On 9/13/2023 12:28 AM, Zi Yan wrote:
From: Zi Yan <ziy@xxxxxxxxxx>
Since compaction code can compact >0 order folios, enable it during the
process.
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
---
mm/compaction.c | 25 ++++++++++---------------
1 file changed, 10 insertions(+), 15 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 4300d877b824..f72af74094de 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1087,11 +1087,17 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
if (PageCompound(page) && !cc->alloc_contig) {
const unsigned int order = compound_order(page);
- if (likely(order <= MAX_ORDER)) {
- low_pfn += (1UL << order) - 1;
- nr_scanned += (1UL << order) - 1;
+ /*
+ * Compacting > pageblock_order pages does not improve
+ * memory fragmentation. Also skip hugetlbfs pages.
+ */
+ if (likely(order >= pageblock_order) || PageHuge(page)) {
IMO, if the compound page order is larger than the requested cc->order,
we should also fail the isolation, cause it also does not improve
fragmentation, right?
+ if (order <= MAX_ORDER) {
+ low_pfn += (1UL << order) - 1;
+ nr_scanned += (1UL << order) - 1;
+ }
+ goto isolate_fail;
}
- goto isolate_fail;
}
/*
@@ -1214,17 +1220,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
goto isolate_abort;
}
}
-
- /*
- * folio become large since the non-locked check,
- * and it's on LRU.
- */
- if (unlikely(folio_test_large(folio) && !cc->alloc_contig)) > - low_pfn += folio_nr_pages(folio) - 1;
- nr_scanned += folio_nr_pages(folio) - 1;
- folio_set_lru(folio);
- goto isolate_fail_put;
- }
I do not think you can remove this validation, since previous validation
is lockless. So under the lock, we need re-check if the compound page
order is larger than pageblock_order or cc->order, that need fail to
isolate.
}
/* The folio is taken off the LRU */
